The overall goal of this study is to improve the care of patients with testicular torsion. Testicular torsion is the spontaneous twisting of the testis and ts blood vessels. It affects at least 1 in 4,000 males younger than age 25 years and is primarily seen in the newborn or the adolescent male. Testicular torsion causes acute severe pain, vascular compromise and death of the testicle if unrelieved within 6-8 hours of onset. Thus, a rapid, accurate diagnosis with rapid surgical detorsion (surgical untwisting of the testis) is imperative. Unfortunately, diagnosis and treatment is often delayed and in 30-70% of torsion cases, the dead testis is surgically removed. This relatively common problem is one of several diagnoses that can cause a painful or acute scrotum, making the clinical diagnosis challenging. While surgical exploration is the gold standard to prove whether torsion is present or absent, unnecessary surgical exploration is undesirable. As well, testicular ultrasound with color Doppler, the most commonly used radiological test, is 89-97% sensitive but slows the speed of the evaluation due to dependence upon a skilled technician. With only 6-8 hours to save the testis, this delay in diagnosis may decrease the chance of salvaging a torsed testis. New sensitive and rapid methods to accurately diagnose torsion are needed. Near-Infrared spectroscopy (NIRS) is a simple and non-invasive technique that assesses the oxygen saturation of deeper body tissue. It has a variety of adult and pediatric human health applications but has not been tested in testicular torsion. We propose to evaluate the usefulness of this modality in human testicular torsion. The overall objectives and specific aims are: 1) To evaluate the utility of NIRS in the diagnosis of testicular torsion versus other causes of the acut scrotum, 2) To assess the sensitivity and specificity of Doppler/ B-mode Ultrasound versus NIRS, and 3) To evaluate the utility of NIRS as an intraoperative and postoperative test for predicting testicular viability after surgical detorsion. Given the high safety profile, the speedof measurement, the non-invasive nature, the projected lower cost and high availability, and the ease of performance without a skilled technician, the innovative application of NIRS for diagnosing testicular torsion may revolutionize and accelerate the care of testicular torsion patients, potentially saving testes and decreasing unnecessary surgeries. PUBLIC HEALTH RELEVANCE: In testicular torsion, the testis and its blood vessels spontaneously twist, causing sudden severe pain and loss of the testicle if not untwisted. Time is crucial and delay in this common diagnosis may decrease the chance of saving a torsed testis, affecting self-esteem and fertility. This study tests a new simple machine which may quickly and easily diagnose torsion, potentially decreasing unnecessary surgeries and saving torsed testes by decreasing the time to diagnosis and corrective surgery.